Quote Originally Posted by Ryuji View Post
Floating element is a commonly used technology in modern, large aperture wide angle lens that can focus rather close. I think several [3]5mm SLR lenses use the same technology, but they are usually (always?) transparent to the user.
Indeed they do. E.g., Nikon calls it CRC "Close Range Correction". My AIS 24/2.8 Nikkor has it and it automatically adjusts with the focus setting. The lens has nice sharp corners even at minimum focus of about 1 foot and at wide apertures. I'm not sure though what would happen if I tried something like using an extension tube or bellows, with the CRC set at infinity. I probably wouldn't notice anything unless I was shooting something flat.

On medium format, I would expect the gains to be a little smaller, unless you are shooting a lot with wide open apertures. I wish I had an FLE 40mm Distagon for my SL66 rig. I've only seen a couple for sale on ebay ever.